Aptamer-Functionalized Electrochemical Sensors for Trace Detection of Water Contaminants

With growing concerns about water pollution, there is an urgent need to develop sensitive, selective, and fast detection technologies. This review provides a critical overview of the recent progress in novel electrochemical aptamer-based sensors (E-aptasensors) developed for priority water contaminants, such as cyanotoxins, pesticides, antibiotics, pathogenic bacteria, nanoplastics, and nitrogen. The combined application of nanomaterials (e.g., gold nanoparticles, graphene, carbon nanotubes, conducting polymers, and metal-organic frameworks) has made great strides in analytical sensing, advancing the detection of fM targets in heterogeneous media. Different electrochemical transductions, such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV), were compared in terms of sensitivity, selectivity, and applicability in authentic samples. Major issues, such as the reproducibility of sensors, matrix interference, and field deployment are addressed, and future directions are proposed, including miniaturization, integration with Internet of Things (IoT) platforms, and regulatory alignment for environmental surveillance.